The classification of
Carassius
has not been well established due to its great variability and wide
distribution. Usually,
Carassius is identified as three species:
C. carassius
,
C. cuvieri
and
C. auratus
, the latter including
several subspecies, such as goldfish. Out of these subspecies,
C. auratus gibelio
have recently been thought of as a valid
species of
Carassius. In this study we collected the 5′end 651 bp segments of the mitochondrial cytochrome c oxidase I
(COI) gene from 128 specimens, including
C. carassius,
C. cuvieri,
C. auratus auratus,
C. auratus gibelio and
C. auratus
langsdorfii
. All three species of
Carassius (
C. carassius,
C. cuvieri,
C. auratus) were found to be valid, meanwhile
genetic differentiation between the Eurasian
C. auratus and Japanese
C. auratus has reached a high level. However,
several haplotypes were shared between
C. auratus auratus and
C. auratus gibelio. Consequently,
C. auratus gibelio
should be regarded as a subspecies of
C. auratus rather than a valid species. Moreover, because both diploids and
triploids exist in
C. auratus auratus and
C. auratus gibelio, ploidy level should not be used as criteria for the
classification of species or subspecies in
Carassius.
